Antimicrobial and antibiotic agents play an important role in current medical therapy regimens. This is particularly true in dermatology where the most effective course of treatment for skin, mucous membrane or hair lesions or infections frequently includes the use of topical antibiotic agents. For example, tetracycline or clindamycin compositions, applied topically, are frequently used in the treatment of acne. The present invention encompasses topical clindamycin phosphate-containing compositions which provide effective antimicrobial performance. These compositions exist in the form of physically stable, aesthetically-pleasing, clear, ringing gels, the formation of which does not require the use of gelling agents which are generally required to form pharmaceutical gels.
Clindamycin derivatives have been disclosed for use in the topical treatment of skin disorders, such as acne. U.S. Pat. No. 3,969,516, Stoughton, issued July 13, 1976, describes a method for treating acne by topically applying antibiotics of the lincomycin family, such as clindamycin phosphate. This patent does not deal with the formulation of clindamycin gels. U.S. Pat. No. 3,487,068 describes the use of clindamycin gels using conventional gelling agents. U.S. Pat. No. 3,856,943, Birkenmeyer, issued Dec. 24, 1974, describes 1'-(beta-hydroxyethyl)-1'-demethylclindamycin compositions which are particularly effective in the treatment of urinary tract infections. These clindamycin analogs can be present as phosphoric acid salts and may be used together with antifungal agents, such as undecylenic acid and sodium caprylate.
Zinc salts of various pharmaceutical actives have also been taught to be effective in the topical treatment of acne. U.S. Pat. No. 4,261,982, Luedders and Willins, issued April 14, 1981, relates to zinc erythromycin compositions which may be administered topically for the treatment of acne. These zinc erythromycin compositions can be formed by combining an erythromycin compound with a zinc salt, such as zinc acetate, zinc propionate, or zinc valerate. There is no disclosure in this patent of gel formulations or of clindamycin-containing compositions. U.S. Pat. No. 4,214,000, Papa, issued July 22, 1980, describes the zinc salt of all-trans-retinoic acid; this compound is taught to exhibit anti-acne efficacy with reduced skin flaking and irritation when compared to conventional retinoic acid therapy. The preferred formulation taught is an alcohol-based gel; all gel formulations described require the presence of conventional gelling agents in order to achieve the desired gel properties. British Patent Specification No. 1,369,622, Shionogi & Co., Ltd., published Oct. 9, 1974, describes pharmaceutical compositions, in the form of stabilized aqueous suspensions of complex gels, which provide protracted corticotropic activity. These compositions comprise a corticotropinactive polypeptide combined with heavy metal compounds (for example, zinc acetate, zinc chloride or zinc hydroxide) and certain nitrogen-containing compounds (such as ethylene diamine). This reference does not describe clindamycin-containing compositions in any form.
However, none of this art suggests that the critical selection and combination of clindamycin phosphate with specific zinc carboxylates in non-aqueous vehicles provide a unique gel-form topical antibiotic composition. In fact, while gels are widely recognized to be a desirable form for a topical composition, most of the gels described in the art require the presence of conventional gelling agents, such as acidic carboxy polymers, to obtain the desired gel properties.
It is, therefore, an object of the present invention to provide effective topical antibiotic compositions containing clindamycin phosphate which are in the form of physically stable, aesthetically-pleasing gels.
It is a further object of the present invention to permit the formulation of clindamycin-containing topical pharmaceutical gel compositions without requiring the use of conventional gelling agents.
It is a still further object of the present invention to provide a method for the effective topical treatment of acne, as well as other clindamycin responsive dermatoses.